India Unveils New Seismic Map Placing Himalayas in Highest-Risk Zone VI

India has introduced a major overhaul of its seismic hazard assessment through a revised Earthquake Design Code, placing the entire Himalayan arc under a newly created Zone VI, the highest-risk category. The update signals a transformative shift in how the country evaluates earthquake threats, with 61% of India now categorised as moderate to high hazard, reshaping expectations for construction, urban planning and infrastructure safety across densely populated regions.

Uniform High-Risk Classification for the Himalayan Arc

Experts note that the new zonation brings long-awaited consistency by removing earlier administrative discrepancies between Zones IV and V. Scientists emphasise that previous maps underestimated the danger from locked fault segments in the central Himalayas, which have not experienced a major rupture for nearly two centuries. The new approach incorporates scientific insights into stress accumulation and rupture propagation along the Himalayan Frontal Thrust.

Scientific Basis of the Updated Zonation

The Bureau of Indian Standards developed the map using probabilistic seismic hazard assessment methods. These integrate data on active faults, maximum potential magnitudes, ground-shaking attenuation, regional tectonics and subsurface lithology. This replaces earlier models reliant on past epicentres and historical damage, which often misrepresented risk in industrial towns and expanding cities. The updated map also mandates that settlements near zone boundaries default to the higher hazard category.

Key Safety Reforms in the Revised Earthquake Design Code

The 2025 code introduces stringent requirements for structural and non-structural elements. Heavy non-structural components exceeding 1% of building weight must be braced to prevent internal collapses. Structures near active faults must account for pulse-like near-fault shaking, while new norms address liquefaction, soil flexibility and site-specific response spectra. Critical infrastructure—such as hospitals, schools, bridges and pipelines—must remain functional after strong earthquakes to ensure emergency continuity.

Exam Oriented Facts

• Entire Himalayan arc is now classified under the new highest-risk Zone VI.
• India’s moderate to high hazard land area has risen from 59% to 61%.
• The 2025 zonation uses probabilistic seismic hazard assessment methods.
• Non-structural components over 1% of building weight must be anchored under new norms.

Exposure Mapping and Regional Variations

For the first time, an exposure window accounts for population density, infrastructure concentration and socioeconomic vulnerability through the PEMA method. This ensures hazard categories reflect potential community impact rather than physical shaking alone. While the Himalayan region underwent extensive reclassification, the southern peninsula experienced only minor scientific refinements due to its relatively stable tectonic behaviour.